title: Bioavailability of ascorbic acid in horses.
abstract: The bioavailability of ascorbic acid administered to thoroughbreds by intramuscular injection was investigated. For intramuscular injection two preparations were studied, and the percentage bioavailability up to 24 h of 10 g of ascorbic acid was 95% +/- 22 in four horses and 60% in two horses with preparations A and B, respectively. Bioavailability at 24 h in three horses injected subcutaneously with 10 g of preparation B was 82%. Intramuscular injection of both preparations was apparently well tolerated while subcutaneous injection of preparation B (pH 6.0) was associated with marked irritancy. In a cross-over trial in seven thoroughbreds the effect of 13 or 15 days of oral administration of crystalline ascorbic acid (20 g) or ascorbyl palmitate (47 g) on plasma ascorbic-acid concentrations was investigated. Marked differences occurred between individuals. There was a greater increase in plasma ascorbic-acid concentration with ascorbyl palmitate compared to ascorbic acid at 6 and 24 h following administration. In two horses there was no increase in plasma ascorbic acid at 6 h following either oral preparation. The finding of lowered plasma ascorbic-acid concentrations following a period of supplementation warrants further investigation to assess its significance.
authors.affiliation: Animal Health Trust, Newmarket, Suffolk, UK.
authors.forename: D H
authors.initials: DH
authors.lastname: Snow
authors.forename: M
authors.initials: M
authors.lastname: Frigg
mesh_terms: D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D001682:Biological Availability; D002940:Circadian Rhythm; D004361:Drug Tolerance; D005260:Female; D006736:Horses / Q000378:metabolism*; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous / Q000662:veterinary; D008297:Male
chemical_list: D001205:Ascorbic Acid